Fluid layer shutters



v Q U U Q June 6, 1961 E. K. KAPRELIAN FLUID LAYER SHUTTERS Filed April 21, 1958 FIGZ IN VEN TOR.

FIG. 3

United States Patent 2,986,982 FLUID LAYER SHUTTERS Edward K. Kaprelian, 29 Riveredge Road, Red Bank, NJ. Filed Apr. 21, 1958, Ser. No. 729,680 3 Claims. (Cl. 95-53) This invention relates to light shutters for photography and related applications.

An object of the invention is to provide a shutter of large size.

Another object of the invention is to provide a shutter in which the light is controlled by means of a layer of opaque fluid.

Still another object of the invention is to provide a shutter having a high operating speed.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in connection with the accompanying drawing in which FIG. 1 shows one form of the invention employing continuous pumping.

FIG. 2 is another form of the invention employing pulsed action.

FIG. 3 is still another form of the invention shown diagrammatically.

The shutter of FIG. 1 comprises a pair of spaced-apart glass plates and 12 held in a frame or support assembly. Plates 10 and 12 are of suitable optical quality and are preferably plane parallel flats. For higher operating pressures Pyrex or quartz would be suitable materials. The support assembly comprises flange 14 and ring 16 for retaining plate 10, and flange 18 and ring 20 for retaining plate 12. The two flanges are attached to each other rigidly as by means of thread 22. As shown in the drawing the flanges maintain a narrow space 24 between the plates. The space extends outwardly from the center and between rings 16 and 20 into an annular manifold 26 formed by flanges 14 and 18. An open ended tube 28 connects to the lowest portion of manifold 26 as shown.

Plate 12 is provided with a hole at its center through which a tube 30 enters perpendicular to the plate surface. The diameter of this tube is approximately .05 that of the glass plate, i.e., for a 10 inch diameter shutter a tube diameter 0.5 inch is adequate. The open end of the tube is flared at 32 as shown, cooperating with a conical member 34 on plate 10 to form therewith a flaring annular passageway.

The lower end of tube 30 connects to the outlet opening of pump 36 which may be of the gear or vane type. The inlet pipe 38 of the pump is submerged in opaque fluid 40 in tank 42. A transverse tube 44 connects to inlet 38 at one end and to electrically actuated metering valve 46 at the other. A tube 48 supplies the valve with compressed air at 50 to 200 lbs/sq. in. pressure. Valve 46 is actuated by controls, not shown, connected to electrical leads 50.

In operation, pump 36 draws opaque fluid 40 from tank 42 and forces it through tube 30, space 24, manifold 26 and out of tube 28 back into tank 42. Suitable screens in tank 42 and at the end of inlet 38 not shown prevent unwanted air bubbles from entering pump 36. In this normal, pumping condition light cannot pass through the opaque film which fills space 24 and the shutter is closed. When the shutter is to be operated an electrical signal from the control circuit to which wires 50 are connected operates valve 46, opening it for a brief period of time and allowing compressed air to fill the intake pipe volume. Pump 36 now sends air under the same pressure as was imparted to the fluid through pipe 30 and space 24 into manifold 26. When the slug of metered air reaches area ice 24 the shutter opens, from the center outwards, as in conventional between-lens shutters and stays open until the air in inlet 38 is consumed and a slug of opaque fluid fills tube 30 and area 24. The shutter then closes from the center outwards, which is opposite to the arrangement in conventional shutters. The length of time that the shut ter is open depends upon the size of the slug of air.

The arrangement for introducing the air can be varied and depends partly on the maximum shutter speed desired and also upon the availability of compressed air. It is highly desirable for example, to introduce the air not at the intake of pump 36 but at its outlet or at some point along tube 30 if maximum shutter speed is desired. Another arrangement is to employ a double valve arrangement whereby high pressure sources of fluid and air are alternately valved into tube 30 at rapid operational speed.

While plates 10 and 12 have been designated as being preferably plane parallel, this is not essential. It is possible to apply a long radius of curvature to both surfaces of plate 12 so that it behaves optically as a zero power meniscus, with the center of curvature to the right, i.e., with its center spaced further from plate 10 than its edge. This would increase the cross sectional area between throat 32 and flow guide 34, as well as constantly increasing the width of passageway 24 from the edge to the center and thereby maintaining its fluid passage area approximately constant along the radius. This reduces flow resistance appreciably and permits the use of lower fluid pressures.

It is obvious that in place of air any transparent fluid which does not mix with the opaque fluid could be employed in place of air. It is possible to employ carbon tetrachloride or a liquid hydrocarbon as the transparent fluid while employing a water base dye or water-borne suspension of colloidal pigment particles as the opaque fluid. In this case the use of a plate 12 having the properties of a zero power meniscus would not be practical without making suitable optical correction elsewhere in the system because of the optical power that would be added. Carving of window 12 is generally unnecessary because the fluid pressure causes some outward bulging of both windows, and increasing the spacing between the windows.

Typical spacing between the windows varies from 0.003 inch to 0.150 inch, the preferred distances lying between 0.005 inch and 0.040 inch. For a 10 inch diameter shutter and a nominal 0.005 inch space, the volume between the plates is 0.40 cubic inch and it is desirable to maintain a 0.15 square inch fluid flow cross section between the plates by suitable bowing. The volume between plates for a 40 inch diameter shutter having a nominal .040 inch spacing is approximately 60 cubic inches, and a fluid flow cross section of 2 to 5 square inches between the plates is desirable. The fluids employed must not foam, and commercially available antifoaming agents are suitable for preventing this condition. The fluids must be free of suspended abrasive solids in order to prevent abrading of the inner surfaces of the windows. The use of wetting agents may or may not be desirable, depending upon whether the opaque shutter liquid is used with air or with a transparent non-miscible liquid. 7

FIG. 2 shows a modification of the invention in which a pulse moves a layer of opaque fluid. In this modification three glass plates 60, 62 and 64 are held in spaceapart parallel relationship by a frame assembly shown generally at 66, forming two fluid receiving spaces 68 and 70 which are equal in volume. Opaque fluid 72 is shown filling space 68. The upper end of space '68 connects to tube 74 which in turn receives a pressure impulse from a high energy source, not shown, which may be a small caliber shell or the shock wave from a condenser discharge spark in a closed liquid filled chamber in a manner well known in the art.

A passageway 76 connects the bottom of space 68 to the bottom of space 70. The volume of this passageway is equal to the volume in space 68. The upper end of space 70 connects into a storage chamber 78 which includes a piston 80 urged downwardly by a spring 82. Space 70 and passageway 76 are normally filled either with air or with a transparent liquid which is not miscible with the opaque fluid. When air is used the usable: volume in chamber 78, with the piston in its uppermost position, is approximately that of passageway 76 and space 70 combined. When a liquid is used the volume of chamber 78 is equal to the combined volumes of passageway 76 and space 70.

In operation a pressure impulse from a rifle cartridge or other suitable pressure source is applied to tube 74, forcing opaque fluid 72 out of space 68 into passageway 76, thereby opening the shutter. The continuing pressure forces fluid 72 up into chamber 70, where it assumes a position similar to that previously occupied in chamber 68, thereby closing the shutter again. The air or liquid previously in chamber 76 and space 70 is now held, under pressure, in chamber 78. Valve means in tube 74, not shown, are employed to maintain the shutter in its second or pressure closed position until a capping shutter or other light safety device is in position at which time the pressure is relieved, permitting the shutter to reassume its original normally closed position.

FIG. 3 shows another arrangement employing a pulse for operating the shutter. In this modification a pair of glass plates 90 and 92 having curved surfaces are seprated by a distance Within the range of .005 to .060 inch and are held in this relationship by an annular frame member 88 and three or more spacer rods, not shown, arranged between the glass plates near their edges. The radius of curvature is 2.5 to 4 times the diameter of the plates and all surfaces have the same radius. A layer of opaque fluid 94 similar in nature to that employed with the shutters of FIGS. 1 and 2 fills the space between the plates. An expansion chamber 96 similar in construction to chamber 78 of FIG. 2 communicates with the space between the plates through a passageway in plate 92, the passageway and the idle part of chamber 96 being filled completely with the opaque fluid.

A flexible, loosely folded annular diaphragm member 98 of fluorinated hydrocarbon sheet or the like is sealed at each edge to the plates, by any suitable means such as metallic bands, adhesive or the like. The opaque fluid fills the lower-most portion of the annular chamber formed by diaphragm member 98 and the plates. The upper portion 100 of this chamber is filled with air or with a transparent liquid which is not miscible with the opaque fluid. The entire chamber 102 in hollow frame member 88 is filled with a liquid, preferably water or some nonflammable liquid. A tube 104 rises upwardly from fluid filled chamber 102.

The shutter is in the normally closed position shown in the drawing, and no light is passed through the plates. To operate, a high pressure pulse is applied to the liquid in chamber 102, the hydraulic pressure causing uniform inward movement of diaphragm 98. The air or transparent liquid 100 is forced into the space between the plates, displacing the opaque liquid and causing it to flow into chamber 96. The shutter is now open and allows light to pass through the plates. When pressure at tube 104 is relieved, the spring and piston in chamber 96 force the opaque liquid back into the space between the plates, thereby ending the passage of light and restoring the shutter to the closed condition shown in FIG. 3.

The source of pressure on the liquid in tube 104 may be the action of a hydraulic piston actuated by a tripped spring or may be the action of an electrical condenser discharge in a water filled chamber connected to the tube.

Still other means for pulsing the shutter are obvious and could be employed if desired.

I claim:

1. A photographic light shutter comprising a pair of parallel, spaced-apart light transmitting plates forming a chamber therebetween, an inlet to said chamber, an outlet from said chamber, means for continuously pumping an opaque liquid under pressure into said chamber through said inlet and out of said outlet whereby said chamber is normally completely filled with said opaque liquid, a source of transparent fluid under pressure, and valve means for substantially instantaneously introducing a volume of said transparent fluid under pressure into said inlet to temporarily displace the opaque liquid within the chamber.

2. A photographic light shutter as claimed in claim 1, said inlet opening into the center of the chamber between said plates, whereby the direction of flow of said opaque fluid is radially outward from the center.

3. A photographic light shutter as claimed in claim 1, the space between said light transmitting plates being in the range of 0.003 inch and 0.150 inch.

References Cited in the file of this patent UNITED STATES PATENTS 2,373,214 Wolkenhauer Apr. 10, 1945 2,481,660 Harrison Sept. 13, 1949 2,537,011 Aparicio Jan. 9, 1951 2,571,894 Kennelly Oct. 16, 1951 

